1. Field of the Invention
The present invention concerns a vehicle steering lock device adapted to lock the steering shaft by the movement of a locking bolt upon rotation of a rotor in a cylinder lock actuated by key-operation made to an electric switch section for an ignition circuit, starter circuit, etc. of a vehicle engine.
More specifically, it relates to a steering lock device of the afore-mentioned type, in which a driver is always enforced to set a shift lever to a parking position whenever he gets off a vehicle drawing out an engine key, so that the vehicle does not happen to run spontaneously during stopping on a downward slope, as well as the steering shaft can surely be prevented from being locked during running by erroneous or accidental turning of the key to the locking position.
2. Description of the Prior Art
Various vehicle steering lock devices of the aforementioned type have already been proposed and put to practical use. For instance, there has been known a locking system in which a switching device for transmission and a steering lock-prevention device in an automotive vehicle are interlocked mechanically with each other, such that the locking operation to a steering shaft by a locking bolt is inhibited at any position other than the vehicle stop position, that is, the parking position of a shift mechanism (refer to U.S. Pat. No. 3490255, Robert D Wight, et al).
Accidental lock to the steering shaft can be avoided by this proposed device. However, since the device is mounted to a narrow space in a steering column in which a shift lever is attached as (a so-called column shift type), the structure is complicated. Further, if it is intended to apply such a device to a floor-shift system in which a shift lever is mounted to a car floor, the mechanical interlocking movement between the shift lever and the steering lock device will be difficult.
It has also been known a device in which the locking operation of such a steering lock device is electrically inhibited by the operation of a solenoid which is energized upon detection of the running state of a vehicle (refer to U.S. Pat. No. 3780032, by M. Suzuki, et al.).
In this device, accidental steering lock during running of the vehicle can be prevented, but the reference mentions nothing about counter-measures for a trouble that a vehicle parking along a downward slope would run spontaneously by itself after a driver gets off the vehicle.
Japanese Patent Laid Open Publication No. Sho 47-44629 discloses a locking device for preventing accidental locking to a steering shaft during running caused by driver's erroneous key operation, etc. In a case if a rotor in a cylinder lock is rotated by key manipulation at an engine stop position and, then, to a steering lock position erroneously, the rotation of the rotor is hindered by a stopper member which is operated upon energization of a solenoid by a signal from a sensor for detecting the running state of the vehicle.
In the proposed device just-mentioned above, however, since the solenoid is energized by a switch that detects the rotating operation of the key toward the lock position and, thereafter, the rotation stopper member is moved to its engaging position with the rotor, if the key manipulation is conducted too quickly, the hindering operation can not always function in time, to some time bring about a risk of locking to the steering shaft.